U.S. patent application number 10/312331 was filed with the patent office on 2003-08-14 for selecting a numbering plan with the use of indicators.
Invention is credited to Kruger, Andrei, Uskela, Sami.
Application Number | 20030152211 10/312331 |
Document ID | / |
Family ID | 8558652 |
Filed Date | 2003-08-14 |
United States Patent
Application |
20030152211 |
Kind Code |
A1 |
Kruger, Andrei ; et
al. |
August 14, 2003 |
Selecting a numbering plan with the use of indicators
Abstract
In order to indicate a numbering plan to be used, an indicator
is defined, by which a subscriber can indicate whether the
subscriber's home numbering plan (203) or a serving network
numbering plan (206) is used when routing a call. The indicator
preferably indicates the use of the home numbering plan, in which
case a telephone number without an indicator uses the serving
network numbering plan.
Inventors: |
Kruger, Andrei; (US)
; Uskela, Sami; (Helsinki, FI) |
Correspondence
Address: |
SQUIRE, SANDERS & DEMPSEY L.L.P.
14TH FLOOR
8000 TOWERS CRESCENT
TYSONS CORNER
VA
22182
US
|
Family ID: |
8558652 |
Appl. No.: |
10/312331 |
Filed: |
December 26, 2002 |
PCT Filed: |
June 25, 2001 |
PCT NO: |
PCT/FI01/00605 |
Current U.S.
Class: |
379/221.02 |
Current CPC
Class: |
H04Q 2213/13399
20130101; H04Q 3/66 20130101; H04Q 2213/13097 20130101; H04Q
2213/13098 20130101; H04Q 2213/13141 20130101; H04Q 2213/13405
20130101; H04Q 2213/13384 20130101; H04Q 2213/1307 20130101 |
Class at
Publication: |
379/221.02 |
International
Class: |
H04M 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2000 |
FI |
20001523 |
Claims
1. A method of selecting a numbering plan to be used in routing a
call of a subscriber in a telecommunication system, in which at
least a home numbering plan defined in the subscriber's home
network and a serving network numbering plan are used;
characterized by the method comprising the following steps:
defining a first indicator, by which it is indicated that the home
numbering plan defined in the subscriber's home network is used in
the call; receiving from the subscriber a telephone number
associated with a call establishment request; in response to a
telephone number with the first indicator, using the home numbering
plan to route the call; and in response to a telephone number
without an indicator, using the numbering plan of the network
serving the subscriber to route the call.
2. A method of selecting a numbering plan to be used in routing a
call of a subscriber in a telecommunication system, in which at
least a home numbering plan defined at least in the subscriber's
home network and a serving network numbering plan are used;
characterized by the method comprising the following steps:
defining a first indicator, by which it is indicated that the
numbering plan of the network serving the subscriber is used in the
call; receiving from the subscriber a telephone number associated
with a call establishment request; in response to a telephone
number with the first indicator, using the serving network
numbering plan to route the call; and in response to a telephone
number without an indicator, using the home numbering plan defined
in the subscriber's home network to route the call.
3. A method as claimed in claim 1 or 2, characterized by receiving
the call establishment request in user equipment; selecting the
numbering plan to be used in the user equipment; and in response to
the home numbering plan, associating in the user equipment the call
establishment request to be transmitted to the network with a
second indicator which indicates to the network that the call is to
be routed according to the home numbering plan; and in response to
the serving network numbering plan, associating in the user
equipment the call establishment request to be transmitted to the
network with a third indicator which indicates to the network that
the call is to be routed according to the serving network numbering
plan.
4. A method as claimed in claim 1, 2 or 3, characterized by the
serving network numbering plan being the home numbering plan, if
the serving network is the home network.
5. A method as claimed in claim 1, 2 or 3, characterized by the
serving network numbering plan being the home network numbering
plan, if the serving network is the home network.
6. A method as claimed in any one of the preceding claims,
characterized by the first indicator being a prefix.
7. A telecommunication system (1) comprising: at least one unit of
user equipment (UE) of a subscriber, the subscriber's home network
(HN) comprising at least one network node (CSCF_H) arranged to
route calls, and at least one visited network (VN) serving the
subscriber, comprising at least one network node (CSCF_V) arranged
to route calls, in which telecommunication system (1) at least a
home numbering plan defined in the subscriber's home network and a
serving network numbering plan are used, characterized in that the
system (1) is arranged to check whether a telephone number received
by the user equipment from the subscriber contains an indicator;
identify a first indicator, by which it is indicated that the home
numbering plan defined in the subscriber's home network is used
when routing a call; in response to the first indicator, use the
home numbering plan defined in the subscriber's home network to
route the call; and in response to a telephone number without an
indicator, use the numbering plan of the network serving the
subscriber to route the call.
8. A telecommunication system (1) comprising: at least one unit of
user equipment (UE) of a subscriber, the subscriber's home network
(HN) comprising at least one network node (CSCF_H) arranged to
route calls, and at least one visited network (VN) serving the
subscriber, comprising at least one network node (CSCF_V) arranged
to route calls, in which telecommunication system (1) at least a
home numbering plan defined in the subscriber's home network and a
serving network numbering plan are used, characterized in that the
system (1) is arranged to check whether a telephone number received
by the user equipment (UE) from the subscriber contains an
indicator; identify a first indicator, by which it is indicated
that the numbering plan of the network serving the subscriber is
used when routing a call; in response to the first indicator, route
the call by using the numbering plan of the network serving the
subscriber; and in response to a telephone number without an
indicator, route the call by using the home numbering plan defined
in the subscriber's home network.
9. A system as claimed in claim 6 or 7, characterized in that the
user equipment is arranged to perform said checking and identifying
and in response to the use of the home numbering plan, to associate
a telephone number to be transmitted to the network with a second
indicator, which indicates that the home numbering plan is used,
and in response to the use of the serving network numbering plan,
to associate a telephone number to be transmitted to the network
with a third indicator, which indicates that the serving network
numbering plan is used.
10. A system as claimed in claim 9, characterized in that the
subscriber is registered in a network node (CSCF_H) of the home
network (HN), and the network node (CSCF_H) of the home network is
arranged to identify the second and the third indicator, and in
response to the call routing by using the serving network numbering
plan, to route the call further to a network node (CSCF_V) of the
visited network serving the subscriber, which node is responsible
for call routing.
11. A system as claimed in claim 9, characterized in that the
subscriber is registered in the network node (CSCF_V) of the
visited network (VN), and the network node (CSCF_V) of the visited
network is arranged to identify the second and the third indicator,
and in response to the call routing by using the home numbering
plan, to route the call further to the network node (CSCF_H) of the
subscriber's home network, which node is responsible for call
routing.
12. A system as claimed in claim 9, characterized in that the
subscriber is registered in the network node (CSCF V) of the
visited network (VN), and the network node (CSCF_V) of the visited
network is arranged to identify the second and the third indicator,
and in response to the call routing by using the home numbering
plan, to find out routing instructions from the home numbering
plan.
13. A system as claimed in claim 7 or 8, characterized in that the
subscriber is registered in the network node (CSCF_H) of the home
network (HN) and the network node (CSCF_H) of the home network is
arranged to perform said checking and identifying, and in response
to the call routing by using the serving network numbering plan, to
route the call further to the network node (CSCF_V) of the visited
network serving the subscriber, which node is responsible for call
routing.
14. A system as claimed in claim 7 or 8, characterized in that the
subscriber is registered in the network node (CSCF_V) of the
visited network (VN), and the network node (CSCF_V) of the visited
network is arranged to perform said checking and identifying and in
response to the call routing by using the home numbering plan, to
route the call further to the network node (CSCF_H) of the
subscriber's home network, which node is responsible for call
routing.
15. A system as claimed in claim 7 or 8, characterized in that the
subscriber is registered in the network node (CSCF_V) of the
visited network (VN), and the network node (CSCF_V) of the visited
network is arranged to perform said checking and identifying and in
response to the call routing by using the home numbering plan, to
find out routing instructions from the home numbering plan.
16. A network node which is arranged to route a call of a
subscriber in a telecommunication system, in which at least a home
numbering plan defined in the subscriber's home network and a
serving network numbering plan are used and in which
telecommunication system a telephone number to be transmitted to
the network contains an indicator, by which the type of a telephone
number is indicated, characterized in that the network node
(CSCF_V, CSCF_H) is arranged to identify a first indicator, by
which it is indicated that the home numbering plan defined in the
subscriber's home network is used in the call; and in response to
the first indicator, route the call by using the home numbering
plan defined in the subscriber's home network.
17. A network node which is arranged to route a call of a
subscriber in a telecommunication system, in which at least a home
numbering plan defined in the subscriber's home network and a
serving network numbering plan are used, characterized in that the
network node (CSCF_V, CSCF_H) is arranged to check whether a
telephone number associated with a call establishment request
contains an indicator; identify a first indicator, by which it is
indicated that the home numbering plan defined in the subscriber's
home network is used in the call; in response to the first
indicator, route the call by using the home numbering plan defined
in the subscriber's home network; and in response to a telephone
number without an indicator, route the call by using the numbering
plan of the network serving the subscriber.
18. A network node which is arranged to route a call of a
subscriber in a telecommunication system, in which at least a home
numbering plan defined in the subscriber's home network and a
serving network numbering plan are used, characterized in that the
network node (CSCF_V, CSCF_H) is arranged to check whether a
telephone number associated with a call establishment request
contains an indicator; identify a first indicator, by which it is
indicated that the numbering plan of the network serving the
subscriber is used in the call; in response to the first indicator,
route the call by using the numbering plan of the network serving
the subscriber; and in response to a telephone number without an
indicator, route the call by using the home numbering plan defined
in the subscriber's home network.
19. User equipment (UE), which is arranged to forward a telephone
number associated with a call establishment request of a subscriber
using the user equipment in a telecommunication system, in which at
least a home numbering plan defined in the subscriber's home
network and a serving network numbering plan are used, which
telephone number to be transmitted to the network contains a type
indicator, by which the type of the telephone number is indicated,
characterized in that the user equipment (UE) is arranged to check
whether the telephone number associated with the call establishment
request contains an indicator; identify a first indicator, by which
it is indicated that the home numbering plan defined in the
subscriber's home network is used when routing a call; in response
to the first indicator, associate the telephone number to be
transmitted to the network with a first type indicator which
indicates to the network that the call is routed by using the home
numbering plan defined in the subscriber's home network; and in
response to the telephone number without an indicator, associate
the telephone number to be transmitted to the network with a second
type indicator which indicates to the network that the call is
routed by using the numbering plan of the network serving the
subscriber.
20. User equipment (UE), which is arranged to forward a telephone
number associated with a call establishment request of a subscriber
using the user equipment in a telecommunication system, in which at
least a home numbering plan defined in the subscriber's home
network and a serving network numbering plan are used, which
telephone number to be transmitted to the network contains a type
indicator, by which the type of the telephone number is indicated,
characterized in that the user equipment (UE) is arranged to check
whether the telephone number associated with the call establishment
request contains an indicator; identify a first indicator, by which
it is indicated that the numbering plan of the network serving the
subscriber is used when routing a call; in response to the first
indicator, associate the telephone number to be transmitted to the
network with a first type indicator which indicates to the network
that the call is routed by using the numbering plan of the network
serving the subscriber; and in response to the telephone number
without an indicator, associate the telephone number to be
transmitted to the network with a second type indicator which
indicates to the network that the call is routed by using the home
numbering plan defined in the subscriber's home network.
21. User equipment (UE), which is arranged to forward a telephone
number associated with a call establishment request of a subscriber
using the user equipment in a telecommunication system, in which at
least a home numbering plan defined in the subscriber's home
network and a serving network numbering plan are used, which
telephone number to be transmitted to the network contains an
indicator, by which the type of the telephone number is indicated,
characterized in that the user equipment (UE) is arranged to
maintain information in its settings, whether the home numbering
plan is used by default; check whether the telephone number
associated with the call establishment request uses the numbering
plan by default; and if the numbering plan by default is the home
numbering plan, in response to the use of the numbering plan by
default, associate the telephone number to be transmitted to the
network with an indicator, which indicates that the call is routed
by using the home numbering plan defined in the subscriber's home
network.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to routing of mobile station calls,
and particularly to the selection of a numbering plan used in call
routing in a visited network.
[0002] Mobile communication systems have been developed to free
people from fixed telephone terminals without hindering their
reachability. Along with the mobile communication systems, a
variety of services provided by these systems have also developed.
At the moment, various new forms of services are being planned for
the current and especially for the future, so-called third
generation mobile communication systems, such as the Universal
Mobile Telecommunication System (UMTS). One of these service forms
is a private numbering plan VPN (Virtual Private Network) enabling
the use of one's own numbers. The VPN is one of the services
representing a subscriber's personal numbering plan in the home
network. In the following, the term "home numbering plan" is used
to refer to these various subscriber numbering plans in the home
network.
[0003] It is also typical of mobile communication systems that a
subscriber can roam from the home network to a network of another
operator, i.e. to a visited network. The aim of the third
generation mobile communication systems is that the subscriber
would be provided with the same services both in the visited
network and in the home network. Thus, the subscriber should be
able to use both a local numbering plan and a home numbering plan
in the visited network. The problem is that the visited network
numbering plan and the home numbering plan may overlap. In
addition, only the home network is aware of the home numbering plan
and the visited network of the local numbers.
[0004] One solution is to make the subscriber use an international
numbering in cases where he wants to use the home numbering plan in
the visited network. The problem of this solution is, however, that
the advantages of the home numbering plan, e.g. shorter numbers
and/or lower call prices, are no longer available.
BRIEF DESCRIPTION OF THE INVENTION
[0005] It is thus an object of the invention to provide a method
and an apparatus for implementing the method to solve the above
problems. The objects of the invention are achieved by methods,
systems, network nodes and user equipment, which are characterized
in what is said in the independent claims. The preferred
embodiments of the invention are disclosed in the dependent
claims.
[0006] The invention is based on the idea that an indicator is
defined, by which a subscriber can indicate whether he wants to use
a home numbering plan or a serving network numbering plan. The
indicator can be defined to refer to the home numbering plan, and
when the indicator is missing, it means that the serving network
numbering plan is taken into use. It is also possible to define the
indicator to refer to the serving network numbering plan, and when
it is missing, it means that the home numbering plan is taken into
use. The home numbering plan contains various subscriber's personal
or group-specific numbering plans in the subscriber home network.
If the subscriber does not have a numbering plan of his own, the
home numbering plan refers to the numbering plan that is generally
used in the home network. The home numbering plan can also be a
combination of a numbering plan specified for the subscriber and a
numbering plan that is generally used in the home network. The
serving network refers to a network, in whose area the subscriber
is and through which the subscriber has access to the system. For
example, the indicator can be a prefix preceding the telephone
number, information after the telephone number or the message
itself, where the telephone is transmitted.
[0007] An advantage of the invention is that it provides a simple
way to indicate to the network, which numbering plan the subscriber
wants to use in his call. Thus the advantages of the home numbering
plan are also available when making a call from the visited network
and local numbers can be used in the short form in the area of the
visited network. In the embodiments, in which the indicator is a
prefix indicating a home numbering plan, an advantage of the
invention is also its backward compatibility: all current numbering
plans function as before.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The invention will now be described in greater detail in
connection with the preferred embodiments, with reference to the
attached drawings, in which
[0009] FIG. 1 is a simplified block diagram of the 3GPP All IP
system;
[0010] FIG. 2 is a flow chart of CSCF operation in a first
preferred embodiment of the invention;
[0011] FIG. 3 is a flow chart of user equipment operation in a
third preferred embodiment of the invention; and
[0012] FIG. 4 is a flow chart of the CSCF operation in the third
preferred embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The present invention can be applied to any
telecommunication system, in which a subscriber can roam to a
visited network and use his home network subscription there. Such
systems include so-called third generation mobile communication
systems, such as the Universal Mobile Telecommunications System
(UMTS) and the IS-41, and the pan-European GSM system (Global
System for Mobile Communications) and the corresponding mobile
communication systems, such as the DCS 1800 (Digital Cellular
System for 1800 MHz) and the PCS (Personal Communication System)
and systems based on the aforementioned systems, such as GSM
2+systems. In the following the invention will be described using
the 3GPP All-IP system, i.e. an UMTS system based on IP technology
(Internet Protocol technology) and specified in the 3GPP (3.sup.rd
generation partnership project), as an example without restricting
the invention thereto. The specifications of mobile communication
systems, and those of the third generation mobile communication
systems in particular, are advancing rapidly; consequently, the
invention may require additional changes. All words and expressions
should therefore be interpreted broadly since they are only
intended to illustrate, not to restrict, the invention.
[0014] The 3GGP All-IP system is based on a GPRS service of the
pan-European GSM system and the intelligent network service
implementation according to the CAMEL (Customised Applications for
Mobile network Enhanced Logic) architecture. The GPRS and the CAMEL
are GSM 2+phase services.
[0015] FIG. 1 shows a simplified network architecture, only
describing elements of a telecommunication system 1 that are
essential in understanding the invention. For the sake of clarity,
it is assumed in FIG. 1 that the serving network is a visited
network, not a home network. The network nodes illustrated in FIG.
1 are logical units, the implementation of which may differ from
what is described. It is obvious to a person skilled in the art
that both the visited network VN and the home network HN have a
similar structure, although they contain different elements in FIG.
1. It is also obvious to a person skilled in the art that the
system 1 may also comprise other functions and structures which
need not be described in greater detail here.
[0016] A call state control function CSCF controls call
establishment, is responsible for routing and contains e.g. a
function corresponding to a switching function of the intelligent
network service. The CSCF provides control of end-to-end IP
telephony services. Signalling associated with the IP telephony,
such as H.323 and SIP, terminates at user equipment UE and the
CSCF. In other words, the CSCF is the network node in which IP
telephony user equipment are registered and through which the
signalling is transferred to the actual IP network IP, for example.
The CSCF comprises IP telephony call state models, which are used
for controlling call establishment with other network nodes, such
as the service control point and IP telephony application servers
(not shown in FIG. 1). The CSCF comprises a subscriber database,
which logically corresponds to a visitor location register in the
GSM system. The CSCF is also responsible for producing billing
information. In the example of FIG. 1, the CSCF_H is a CSCF in the
home network HN and the CSCF_V is a CSCF in the visited network VN.
The CSCF operation according to the invention is explained in
greater detail in connection with FIGS. 2 and 4.
[0017] The user equipment UE comprises an actual terminal and an
identification card USIM, also called a subscriber identification
unit, detachably connected thereto. In this connection, the user
equipment UE generally refers to a unity comprising the actual
terminal and the subscriber identification unit. The subscriber
identification unit USIM is a smart card which comprises subscriber
identity and which performs authentication algorithms and stores
authentication and cipher keys and subscription information
necessary for the user equipment. A home network CSCF_H address,
for example, may be stored in the subscriber identification unit
USIM. The actual terminal can be any equipment capable of
communicating in a mobile communication system. The terminal can
thus be a simple terminal intended only for speech, or it can be a
terminal for various services, operating as a service platform and
supporting loading and carrying out different service-related
functions. The terminal can also be a combination of various
devices, for example a multimedia computer with a Nokia card phone
connected thereto to provide a mobile connection. The user
equipment operation according to a third and a fourth preferred
embodiment of the invention is explained in greater detail in
connection with FIG. 3.
[0018] In the example of FIG. 1, the visited network VN also
comprises a core network CN and a UMTS terrestrial radio access
network UTRAN and a service look-up server SLS. The home network HN
also comprises the corresponding parts, but they are not shown in
FIG. 1.
[0019] The UTRAN is formed of a group of radio network subsystems
(not shown in FIG. 1), which are connected to a core network CN.
The core network CN can be connected to external networks, such as
IP networks IP. In the example of FIG. 1, the core network CN
comprises a serving GPRS (General Packet Radio Service) support
node SGSN serving the user equipment UE in its service area and a
gateway GPRS support node GGSN connecting the operator to the
external systems of the GPRS network, such as to the IP network IP.
The GGSN functions as a router between the external address and the
internal routing information (e.g. SGSN). Other types of core
networks, such as IS-41, may comprise other network elements.
[0020] The support nodes SGSN and GGSN are usually interconnected
by a backbone network (not shown in the figure). It is to be noted
that the SGSN and GGSN functionalities can also be physically
connected to the same network node, in which case the backbone
network of the operator is not required. Logically, however, the
nodes are different nodes. The IP telephony is in practice
invisible to the elements of the core network. For the support
nodes SGSN and GGSN, the IP telephony is only a PDP context with
certain service quality requirements. The signalling associated
with the IP telephony terminates at the user equipment and the
CSCF, so there is no need for the SGSN or GGSN to understand it,
and thus they do not participate in call routing.
[0021] In the example of FIG. 1, a service look-up server SLS is
connected to the GGSN. The SLS preferably comprises a visited
network CSCF_V address. The SLS may also comprise the alarm numbers
and/or free service numbers of the visited network and other
specific information relating to the visited network, and the user
equipment can request for this information after the attachment to
the GPRS network. Using the help of the SLS, for example, the user
equipment UE can find out the visited network CSCF_V address. The
user equipment UE can find the SLS by broadcasting an inquiry to
which the SLS replies. The user equipment UE obtains the address
from the reply, and it may request from the SLS for further
information. The SLS address can also be obtained from the SGSN or
GGSN also during the GPRS attachment procedure or immediately after
it.
[0022] A home subscriber server HSS is a core network element,
which is illustrated only in the home network HN in the example of
FIG. 1. The home subscriber server HSS logically corresponds to the
home location register in the GSM system, and subscriber data for
each subscriber of the home network are stored therein permanently
or semi-permanently such that the subscriber data are combined with
a subscriber identifier, which, for example, is an IMSI in the GSM
system. Subscriber data may for example contain the home network
CSCF_H address, which can be transferred to the visited network
CSCF_V during the registration.
[0023] IP telephony is a general term which covers services from
the standard voice telephony VoIP (Voice over IP) to multimedia
applications using IP data, voice and video in the IP telephony. In
addition to the IP telephony, the above system supports other
applications, such as the access to the Internet or an intranet.
Correspondingly, an IP call refers to a call which utilizes
IP-based user data flow and signalling. The user data may comprise
various components, such as voice, video image and data. In
addition to calls, the IP telephony may comprise call-like
services, which can be unidirectional, directed to a group (or
groups) or broadcast in a given area, for example.
[0024] In addition to prior art means, the system and its network
nodes implementing the functionality of the present invention
comprise means for implementing functions described in greater
detail in connection with FIGS. 2, 3 and 4. More specifically, they
comprise means for identifying a possible indicator in a telephone
number and for call routing according to a numbering plan indicated
by the indicator or the missing of the indicator. The existing
network nodes comprise processors and memory that can be utilized
in the functions of the invention. All changes necessary for
implementing the invention can be carried out as additional or
updated software routines and/or by application circuits
(ASIC).
[0025] The invention is described in FIGS. 2, 3 and 4, assuming
that an indicator is a prefix and that call, whose telephone number
begins with a prefix ++, is routed according to a home numbering
plan and a number without a prefix is routed according to a serving
network numbering plan. The invention is not restricted to the
prefix ++ in any way, but other indicators can be used as well.
Thus, in the examples of FIGS. 2, 3 and 4 there are three different
numbering plans available for the subscriber:
[0026] ++NNN is a home numbering plan
[0027] +NNN is an international network numbering plan
[0028] NNN is a serving network numbering plan.
[0029] FIG. 2 shows the operation of a CSCF controlling the call,
when a call utilizing IP telephony is made from user equipment UE.
For the sake of clarity it is assumed that the user equipment has
made itself known to the access network by performing a GPRS attach
operation. In the GPRS attach procedure, the SGSN creates a
mobility management context (MM context) and a logical link LLC
(Logical Link Control) is provided between a mobile station MS and
a SGSN node in the protocol layer. For the sake of clarity it is
further assumed that the user equipment has activated a PDP
context, i.e. a packet data address it wishes to use. The PDP
context specifies different data transfer parameters, such as a PDP
type (X.25 or IP, for example), a PDP address (IP address, for
example), quality of service QoS and an NSAPI (Network Service
Access Point Identifier). Furthermore, it is assumed for the sake
of clarity that the user equipment is registered in the CSCF and
that the call is routed to that CSCF. In other words, the CSCF in
which the user equipment is registered controls the call
establishment of user equipment. It is irrelevant to the invention
how the CSCF is selected during the registration and also how the
different CSCF addresses are found out.
[0030] For the sake of clarity, it is also assumed that the user of
the user equipment uses numbers and prefixes according to the
numbering plans. In other words, it is assumed that the telephone
number is valid and does not, for example, contain a minus sign as
a prefix. It is also assumed that no call barrings have been
set.
[0031] With reference to FIG. 2, in step 201 a telephone number is
received, to which the user of the user equipment wants to call. In
step 202 it is checked whether the telephone number contains a
prefix ++. If it does, a home numbering plan is used (step
203).
[0032] If the telephone number did not have the prefix ++(step
202), it is checked in step 204, whether it has a prefix +. If it
does, it deals with an international numbering plan (step 205)
which is used for call routing.
[0033] If the call has no prefix (i.e. it does not have the prefix
++ nor the prefix +), a serving network numbering plan is used
(step 206).
[0034] In a second preferred embodiment of the invention, the CSCF
checks after step 201, whether the subscriber calls from the home
network. If he does, the call is routed according to the prior art
on the basis of the telephone number. If the subscriber calls from
the visited network, it is continued from step 202 in FIG. 2.
[0035] The invention is described in FIG. 2, assuming for the sake
of clarity that the number to be transmitted from the user
equipment to the network may contain prefixes in text format, such
as prefixes ++, which is possible when using Internet type
addresses. However, this is not the case for example in the GSM
system. In the GSM system, the user equipment identifies the prefix
(++, +or no prefix) given by the user and associates the call
establishment request with an indicator TON (type of number) as a
prefix, the TON indicating, what kind of a number it deals with.
Thus, a new type of a telephone number TON has to be defined in
these systems, indicating that the home numbering plan is now
used.
[0036] FIGS. 3 and 4 illustrate the operation according to the
third preferred embodiment of the invention, whereby the number
sent to the network always contains the prefix TON which indicates
what kind of a number is used. The same assumptions are made in
FIGS. 3 and 4 as in FIG. 2. In addition, it is assumed for the sake
of clarity that only three different prefixes TON are used. It is
obvious to a person skilled in the art how the invention is applied
if there are more different prefixes.
[0037] FIG. 3 illustrates the user equipment operation in the third
preferred embodiment of the invention. In step 301 a telephone
number is received, to which number the user of the user equipment
wants to call. It is checked in step 302, whether the telephone
number contains the prefix ++. If it contained the prefix ++, the
user wants to use the home numbering plan. As the type of a
telephone number TON, "home" is selected in step 303 and the type
of the telephone number and the actual telephone number are
transmitted to the network in step 307. In step 307, the telephone
number to be transmitted always comprises the prefix TON and the
actual number.
[0038] If the telephone number contained no prefix ++ (step 302),
it is checked in step 304 whether it has the prefix +. If it does,
the user wants to use the international numbering plan, and in step
305, "international (int)" is selected as the type of the telephone
number. Thereafter, the type of the telephone number TON and the
actual telephone number are transmitted to the network in step
307.
[0039] If the call does not contain a prefix (i.e. it does not
contain the prefix ++ nor the prefix +), the user wants to use the
serving network numbering plan. In step 306, "local" is selected as
the type of the telephone number and the type of the telephone
number and the actual telephone number are transmitted to the
network in step 307. In some other preferred embodiment of the
invention, the serving network numbering plan can also be indicated
by some other type of TON.
[0040] In the fourth preferred embodiment of the invention, the
user equipment is adapted to always set "home" (TON=home) as the
type of the telephone number chosen by the user, unless the user
indicates something else with his choice. For instance, using the
user equipment settings, it can be selected whether the home
numbering is on or off. In this case, the user equipment checks the
value of this setting before step 302, and if the home numbering is
off, it is continued from step 302. If the home numbering is on,
the user equipment checks whether the user has given an
international number (step 304) and if he has not, the user
equipment marks "home" as the type of the telephone number. In
other words, in the fourth preferred embodiment of the invention
the home numbering plan is used by default unless the subscriber
indicates another numbering plan with his selection.
[0041] FIG. 4 shows CSCF operation in the third preferred
embodiment of the invention. In step 401, both the TON indicating
the type of the telephone number and the actual number to which the
user of the user equipment wants to call are received. It is
checked in step 402 whether the type of the telephone number is
"home". If it is, the home numbering plan is used (step 403).
[0042] If the telephone number was not of the type "home" (step
402), it is checked in step 404 whether it is of the type
"international". If it is, it deals with the international
numbering plan (step 405), which is used for routing the call.
[0043] If the telephone number was not of the type "home" nor of
the type "international", it is "local", in which case the serving
network numbering plan is used (step 406).
[0044] In the above embodiments it is assumed that if the user
calls from the visited network area, the serving network numbering
plan is the numbering plan of the visited network. If the user
calls from the home network area, the serving network numbering
plan is the home numbering plan in the first, second, third or
fourth preferred embodiment of the invention.
[0045] In a preferred embodiment of the invention, when calling
from the home network, the serving network numbering plan is the
home network numbering plan, i.e. then the subscriber's own
numbering plan will not be used.
[0046] User Equipment Registered in the Home Network CSCF
[0047] If the user equipment always registers in the home network
CSCF, the user equipment that registers in the visited network area
must during the registration, for instance, transmit the visited
network CSCF address to the home network CSCF, since, when making a
local call in the visited network, the call signalling must finally
be routed to the CSCF that is aware of the visited network
numbering.
[0048] The home network CSCF controls the call when the home
numbering plan is used (for example step 203 and step 206, when
calling from the home network area in the first embodiment of the
invention) or when the home network numbering plan is used (for
example step 206, when calling from the home network area in the
second embodiment of the invention).
[0049] If the visited network numbering plan is used (for example
step 206, when calling from the visited network area), the home
network CSCF routes the call to the visited network CSCF and it may
also transfer the call control to the visited network.
Alternatively, the home network CSCF itself can control the call,
although the visited network CSCF is responsible for the
routing.
[0050] When using the international numbering plan, the home
network CSCF either controls the call and takes care of the routing
itself or it alternatively transfers the control (and the routing)
to the visited network CSCF. Both CSCFs can perform the routing by
using the international numbering plan.
[0051] Alarm calls made from the visited network and/or free calls
of the visited network may use the above route or they can be
identified by the user equipment as special calls, in which case
the call establishment procedure triggered by them differs from
what is shown in FIGS. 2, 3 and 4, and the calls are always routed
directly to the visited network CSCF. The user equipment can, for
example, receive from the SLS the free numbers and alarm numbers of
the visited network to identify the calls as special calls.
[0052] User Equipment Registered in the Visited Network CSCF
[0053] The visited network CSCF controls the call when the visited
network numbering plan is used (for example step 206).
[0054] If the home numbering plan is used (for example step 203),
the visited network CSCF may route the call to the home network
CSCF and it may even transfer the call control to the home network.
The visited network CSCF receives the home network CSCF address,
for example, from the user equipment UE by concluding it on the
basis of the identifier of the subscriber using the user equipment
or by requesting it from the HSS. Alternatively, the visited
network CSCF can control the call itself and request from the home
network in each call, for example, where the call should be routed.
It is also possible that the entire home numbering plan of the
subscriber is transferred to the visited CSCF from the HSS, for
example, and the visited CSCF uses it in cases where the user of
the user equipment has dialled the prefix ++ in front of the
telephone number (whereby, depending on the embodiment, the CSCF
receives either the prefix ++ or the prefix TON=home).
[0055] When the international numbering plan is used, the visited
network CSCF either controls the call and takes care of the call
routing itself or it alternatively transfers the control (and the
routing) to the home network CSCF.
[0056] Although the invention is described above assuming that a
prefix indicates that a home numbering plan is used, it is obvious
to a person skilled in the art that the invention can also be
applied to solutions, in which the prefix indicates that a serving
network numbering plan is used and that calls without a prefix are
routed according to the home numbering plan.
[0057] By means of the prefix, the user of the user equipment can
also select, whether a call is controlled by a serving network call
control node or a home network call control node. In these
embodiments the call control is transferred, if necessary, to the
node of the network that the user has indicated by the prefix.
[0058] Although the invention is described above assuming that an
indicator is a prefix, it is obvious to a person skilled in the art
that the invention can also be applied to solutions in which the
indicator is given after a telephone number or in which, at least
in information sent to a network, the indicator is the message, in
which the telephone number is transmitted.
[0059] It is to be understood that the above description and the
related figures are only intended to illustrate the present
invention. Different variations and modifications of the invention
will be obvious to a person skilled in the art without deviating
from the scope and spirit of the invention disclosed in the
attached claims.
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